DMA is a technique that allows for hardware in a computer to access system memory independently of the system processor. Because the processor is not involved in the transfer of data, DMA is usually fast. DMA is very useful for example in real-time applications and for making backups. A few illustrative examples of hardware that use DMA circuits include sound cards, hard disk controllers and computer subsystems. Traditional DMA circuits have one or more physical channels where each physical channel is a point-to-point communication link connected from a source to a destination port. Although useful, the point-to-point links make the system inflexible and may limit the performance of the DMA for some applications.
Some traditional DMA circuits with multiple logical channels use several physical channels to perform concurrent transfers with each physical channel being associated to a separate data First-In-First-Out (FIFO) memory. With this type of design, there is a limit in the number of concurrent logical channels available since it is not possible to have more concurrent logical channels active than the number of physical channels that are available. Another problem with some DMA circuits is that their data FIFOs may be under utilized based on the channel transfer context. A need thus exists in the art for a storage circuit that can improve the reuse of the DMA and provide better flexibility and efficiency.